#include <stdio.h>
#include <unistd.h>
#include <alloca.h>
#include <string.h>

int main (void)
{
	size_t n = confstr (_CS_GNU_LIBC_VERSION, NULL, 0);
	if (n > 0)
	{
		char *buf = alloca (n);
		confstr (_CS_GNU_LIBC_VERSION, buf, n);
		printf("%s\n", buf);
	}
	return 0;
}